Surface characterization of polyvinylamine/SBA-15 hybrid material

The surface of mesoporous silica (SBA-15) was functionalized by an introduction of polymer containing amine groups. The proposed, novel modification route consisted of three main stages including: (i) grafting of vinyltriethoxysilane (VTS) on the surface silanols, (ii) radical copolymerization of grafted VTS with N-vinylformamide and (iii) acid hydrolysis of poly(N-vinylformamide) (PNVF) to poly(vinylamine). The SBA-15 structure remained stable during all the modification steps as confirmed by X-ray powder diffraction and low-temperature N2 adsorption. Changes in the surface composition were studied by elemental analysis and thermogravimetry, whereas the nature of surface species was identified by diffuse reflectance infrared Fourier transform and X-ray photoelectron spectroscopy. The optimal amount of introduced PNVF, which allowed to obtain the highest dispersion of amine functionalities and protect the pore system of mesoporous support against total blocking by the formed polymer, was determined.